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(No Model.)

M. G. KELLOGG. MULTIPLE SWITGHBOARD. No. 592,303. Patented Oct. 26,1897.

li/em for' 77u., Q /dww/,

IINTnn STATES PATENT Prion.

MILO c. KnLLOeG, OF CHICAGO, ILLINOIS, AssIGNOR To THE KELLOGGswrrCnnoARD AND SUPPLY COMPANY, OP SAME PLACE.

MULTIPLE SWITCHBOARD.

SPECIFICATION forming part of Letters Patent No. 592,303, dated October26, 1897.

Application tiled May 19,1887. Serial No. 238,723. (No model.)

T o all whom, t may concern:

Bc it known that I, MILO G. KELLOGG, of Chicago, (I'Iyde Parle)Illinois, have invented certain new and useful Improvements in MultipleSwitchboards for Telephone-Exchanges, of which the following is a full,clear, concise, and exact description, reference being had to theaccompanying drawings, forming a part of this specification.

My invention relates to telephone-exchan ge systems in which thesubscribers lines are normally grounded at the central office.

It consists, iirst, of a multiple-switchboard system of operating anexchange and testing at any board to determine whether any given line isin use, which system I shall hereinafter describe and claim in detail.

It consists, secondly, of a certain construction of spring-jack switch,which I shall h ereinafter describe and claim in detail, said switchbeing adapted for use in said multipleswitchboard system and in othersystems of telephone-exchange switchboards.

It consists, thirdly, of a certain system of cords with plugs,apparatus, and circuits for answering, calling, switching, testing, andclearing out subscribers lines, which I shall hereinafter describe andclaim in detail, said system being applicable to saidmultipleswitchboard system and to other systems of telephone-exchangeswitchboards.

In my multiple-switchboard system I place as many switchboards in thecentral Oflce as are found necessary or desirable in order to properlyanswer the calls and connect and disconnect the subscribers lines. Oneach board I place for each line which centers at the office a spring-jack or similar switch having three insulated conta-ct -points, two ofwhich are normally in Contact, said switch being adapted to receive aplug, and when the plug is inserted to disconnect the two points andconnect one of them to the fiexible conducting-cord of the plug and theother one of them to the other contact-point of the three, and when theplug is withdrawn to again connect the contact-points which are normallyin contact and disconnect the other point from either of them.

Figures 1n and lb of the drawings are front views of sections of twomultiple switchboards to which the same wires are connected. Fig. 2shows a complete diagram of the boards with their connections and allthe central- Oiiice apparatus, circuits, and connections necessary tooperate them according to my invention.

In the drawings like parts and apparatus are indicated by the sameletters of reference.

In Fig. 2, A is a sectional View of the switchboard shown in Fig. l, asindicated by line CZ c, and A is a sectional view of the switchboardshown in Fig. lb, as indicated by line CZ e.

a h represent rubber strips on which the metal parts of the spring-jackswitches are mounted. These strips may be long enough to receive anyconvenient number of springjack parts.

YZ l are rectilinear holes through the fronts and at thc edges of thestrips adapted to receive the switch-plugs. The contact-springs g g aremounted to the rear of and are parallel to the holes Z Z to which theybelong, as shown. The contact-points h 7i, on which the contact-springsor spring-levers g g normally bear,pass through the rubber strips, asshown, and each has a connecting-piece 7L anda contact-piece orextension 7L", as shown, extending to the front of the point and alongthe lower face of the switch-hole. In the front of the switch-holes andalong their lower faces I place the contact-pieces /L' z', as shown.These pieces come in proximity to but do not touch the contact-pieces h,and they extend far enough to the front of their respective holes sothat test-plugs may be applied to them. The switch-plugs aresubstantially as shown and as will hereinafter be described.

The several parts mentioned above are so made, shaped, arranged, andadjusted that when a switch-plug is inserted into a switchhole, asshown, it raises the spring-lever in the rear of the hole from thecontact-point on which it normally bears, andthe flexible cord isconnected to the spring-lever,whilc the contact-point h and thecontact-piece t' are electrically connected through the medium of thepiece m of thc switch-plug, which then touches c' and 7L" of the switch.

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' pointhand connecting-piece 7L of that switch a Each section of the'rubber strip, with 'its spring-lever, contact point, conta-ctpieces',and vthe. hole, all arranged and operating as above, may be called aspring-jack switch. The rubber strips are placed one above the other, asshown. The lower edge of one strip therefore provides the upper edges ofthe holes in the strip which is below it. The holes may be of anyconvenient shape adapted to the shapes and arrangement of the partsused.

Two subscribers lines are shown. They are marked line No. l and line No.2. s s are the spring-jack switches of line No. l on the two boardsshown, and r r' are the switches of line No. 2 on the two lboards shown.The circuits of the lines are as follows: Line No.

1, for instance, after entering the office passes4 iirst tospring-leverg of switch s', and thence through contact-point h and connecting-pieceh of that switch and wire s to spring-lever g of switch s, and thencethrough contactand wire s/H to its annunciator w, and thence to ground.The contact-pieces t' and t' of switches s and s are connected togetherby wire 3", as shown. The other lines of the eX- change would beconnected to their switches on the different boards and to ground inlike manner, and the contact-pieces t' i which belong to the switches ofa line would also be connected together in a like manner to that above.Other boards might be added' to the exchange, and the connections'oflines and the switches on the different boards would be th'ccords andadapted to be inserted into the line-switches.

m m are the metal pieces of the plugs, adapted to come in Contact withthe springlevers 'g of a switch and connect therewith the cords of theplugs.

fm m are metal pieces'of the plugs, adapted to come in lcontact with thepieces h" and t' and connect them together.

n n are the rubber insulations of the plugs. The pieces m m extend tothe bottom of the plugs, as shown, and are adapted to rest on the metalstrip o, as shown, and normally connect the cords with the ground. Theplugs should be inserted into the switches in such a position that theconnections above described will be made. A plug is shown thus insertedin switch s in Fig. 2. Weights in the usual manner, or similar device's,may be vused to bring the bottoms of the plugs on o and form goodconnection from the cords to the ground.

Y is a looping-in switch.

g/ y and .c z are the contact-bolts of the switch, on which the'operatormay at will place the pair of switch-levers.

7c is thecalling-key, constructed, connected, and operating as shown. Aswitch or similar device might be used in its place.

o is a clearing-out annunciator.

tis the operators telephone, B is her signalin g generator or battery,and B is her testing-battery. The circuits are substantially as shown.

The cross-piece between the levers of the switch 'Y may be of rubber, asis usual.

The letter G in each case represents a ground connection.

It is evident that when a switch-plug is placed in a line-switch, asdescribed, (the other plug of the pair being used remaining on strip 0,)and the levers of the switch Y are placed on y y the line isdisconnected from theground through its annunciator and is groundedthrough the operators telephone, and the contact-piece i of theline-'switch (and consequently all contact-pieces t' to which it isconnected) is grounded through the switchboard-circuit andcalling-annunciator ot' the line. in another line-switch, that line isalso disconnected from the ground and the contactpieces t' of .that-line are also grounded and similar to the above and such as will beevij the two lines are connected together for conversation. Thecontact-pieces t of a line are normally (or when there is no plug in any`switch of. the line) disconnected from the ground.

The testing system is as follows: Vhen an operator desires to test anyline at her board to see whether it is in use at another board, shemoves the levers of the switch Y of a pair ofxcords to the bolts y y,and, placing. the piece m of one of the plugs of the cords on thetest-piece t' of the line to be tested, she will hear a click inhertelephone if the line is in use and will hear nothing if the line is notin use. The other plug of the pair may, when the testis made, remain onthe strip o or may be in the spring-jack switch of another line. If theline tested is in use when the test is made, there will be a circuitfrom the ground to the other plug of the pair used, either through stripo or a subscribers line, through the telephone and testing-battery, thetest-bolt at the board tested, the wire between that bolt and thetest-bolt when the 'line is switched, and thence by the piece m of theplug by which the switching is done to the ground, and the test-battery,being thus in a closed circuit with the telephone, will occasion a clickin the telephone when the test is made. If the line is not in use, therewill be no such closed circuit and consequently no click in thetelephone.

If the other plug of the pair is placed IIO The method of operating theexchange system at either board, including answering calls, makingconnections, sending signals, clearing out connections, duc., is such aswill be apparent on an examination of the apparatus and circuits shown.

It is obvious that some features of my exchange may be used on lineshaving impedancecoils or annunciators in circuit-s permanently connectedto line.

The testbolts of a line on the different boards maybe separate anddistinct from the contact pieces of the switches which are crossed withthe ground connection of the line, provided they are in electricconnection with said pieces.

I claim as my invention and desire tosecure by Letters Patentl. Thecombination, with a strip of insulating material having a plug-holethrough it, transverse to its front, of the metal parts of a spring-jackswitch mounted thereon, said parts containing a spring-lever placedtransverse to the front of said strip and in rear of the plug-hole, andtwo contact-pieces, normally insulated from each other, said contact-pieces being mounted with their contactsurfaces in the same plane,and on the face of said plughole and one of said contactpieces beingnormally (or when a plug is not in said hole) in Contact with saidspring, sub stantially as and for the purpose set forth.

2. A spring-jack switch with its metal parts mounted on a strip ofinsulating material, said strip having a plug-hole through it,transverse to its front, and said metal parts consisting of aspring-lever mounted in the rear of said plug-hole, and transverse tothe front of said strip, and two contact-pieces normally insulated fromeach other, said pieces being mounted with their contact-surfaces in thesame plane and on the face of said plughole and one of saidcontactwpieces being normally (or when a plug is not in said hole) incontact with said spring, in combination with a switch-plug with twocontact-surfaces, insulated from each other, and one of which isconnected with a switch-cord, said plug being adapted to be insertedinto said hole, and when inserted to disconnect said spring from saidnormal contact with one of said contactpieces, and connect said springwith said switch-cord, and at the same time electrically connecttogether said two contact-pieces, and insulate them from said lever andswitchcord, substantially as and for the purpose set forth.

3. A spring-jack switch with its metal parts mounted on astrip ofinsulating material, said strip having a rectilinear plug-hole throughit, transverse to its front, and said metal parts consisting of aspringlever mounted in the rear of said plug-hole, and transverse to thefront of said strip, and the two contact-pieces normally insulated fromeach other, both pieces being mounted with their contact-surfaces in thesame plane, and on one of the faces of said rectilinear plug-hole, andone of said contact-pieces being normally (or when a plug is not in saidhole) in contact with said spring, in combination with a switch-plugadapted to lit said plughole, and having two contact-pieces insulatedfrom each other, and to one of which is connected a switch-cord, saidplug on its insertion disconnecting said spring-lever from said normalcontact with one of said contact-pieces, and connecting it with saidswitch-cord, and at the same time electrically connecting together saidtwocontact-pieces and insulating them from said lever and switch-cord,substantially as and for the purpose set forth.

4. In a spring jack switch, the contactpieces h and t' mounted along theface of the switch-hole, and with contact-surfaces in the same plane, incombination with the springlever g, substantially as and for the purposeset forth.

5. In a spring-jack-switch device, the contact-piecesh and i, mountedalong the face of the switch-hole, and with contact-surfaces in the sameplane, and the spring-lever g, in combination with the switclrplug, withcontact-pieces m and m', substantially as and for the purpose set forth.

6. In a spring-jack switch, the combination of a contact point or piecehaving a metal surface in line with a face of the switch-hole andextending toward the front of and along said hole, a springcontact-lever in the rear of said hole and transverse to it, andnormally or when no switch-plug is in the hole, in contact with saidcontact-point, anda contact-piece, normally insulated from the otherpieces, mounted on a face of said hole with its contacteur-face in thesame plane as said metal surface, and adjacent to it and reach` ing toor near the front of said hole, substantially as and for the purpose setforth.

7. The combination, with a spring -jack switch having two contact-pointswhich are normally (or when no plug is in the switchh'oleYin contact,and a third contact-point which is normally insulated from the othertwo, a telephone-line connected to one and a ground connected totheother of said contact-points, which are normally in contact, of aswitch-plug and a switch-cord, said plug having two insulatedcontact-pieces to one of which is connected said switch cord, andadapted, on the insertion of the plug into the switch-hole to separateand insulate the points which are normally in contact, connect the linecontact-point with the cord, and said third contact-point with thcground contactpoint.

8. In a multiple-switchboard exchange, a closed test-circuit for aground-circuit line which is in use, said circuit including, in theorder named, a ground connection, a test out- (it and plug, a testcontact-piece for the line temporarily connected to said plug fortesting, thence to a contact in some other switch of the line where theline is switched for use,

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and thencey to a contact directly connected thereto, mounted on the plugin said switch, but not then connected with the circuit of theline, andthence to a second switch-contact connected to said plug-contact whilethe plug is in the switch Vbut otherwise insulated from. said circuitconnection,thence to ground.

9. In a multiple-switchboard exchange, a closed test-circuit for aground-circuit line which isin use, said circuit including, in the ordernamed, a ground connection, a test instrument and plug a testcontact-piece for .the line temporarily connected to said plug fortesting, thence to a circuit connection connecting all the contacts ot'said line together, thence toa contact in some other switch of the linewhere the line is switched for use, and thence to a contact directlyconnected thereto mounted oni the plug in said switch but notthenconnected with the circuitof the line, and thence to alsecondswitch-contact connected to said plug-contact while the plug is in theswitch but otherwise insulated from said circuit connection, thence tothe cut-0R portion of the line through any pair or pairs of normallyclosed jack-contacts which may be in said portion, andl to ground, andmeans in said test-circuit to cause said test instrument to'respond whenconnected to said closed test-circuit.

10; In a multiple-switchboard exchange, two ormore multiple boards,switches, one for eachline oneach board, each switch having threecontacts, atest-contact, a contact connected'to the ground, and acontact connected to the line, said"` test-contacts being electrically`united butr disconnected normally from thelother contacts, and plugs ateachboard adapted' to be inserted into the switches and each having aconducting-piece adapted to connect said test-contact and saidgroundcontact ofthe switch bycross-connecting or electrically bridgingsaid/test and: ground contacts of the switch without connecting saidtest-contact to the line-circuit.

v 11.` In a multiple -switchboardl exchange, two or more switchboards,switches, one for each line on two or more boards, each switch having atest-contact, saidV test-contacts for each linebeing'connected togetherand. normally ung'rounded, a contact connected to the ground, andacontact connected to the line, switch-plugs-at each board, eachfplugadapted to'be inserted into each switch at each board and each havingtwo insulated contacts, onel the test and ground contacts of the switchin i whichitis inserted and thereby cross-connect or electrically bridgesaid test and said ground contacts.

l2. Ina multiple-switchboard exchange, test-contacts one at each board,foreach line, the test-contacts of each line being electrically unitedtogether and normally ungrounded, a common grounded conductor, a circuitconnection between said test-contacts and said common groundedconductor, normally open but closed or bridged by a plug-contact adaptedto form apart of said circuit connection while the line is switched foruse, a test outt' connected on one side to said conductor, and on theother adapted to be connected to atest-contact for testing, andatest-battery for the test-circuit when established.

13. Inl a multiple-switchboard exchange, switches, one at each of two ormore boards for each line, a common conductor, a contact in each switchnormally insulated therefrom, a circuit connecting said contacts, oneadditional contact, in each switch connected to said common conductor, abridgingv or crossconnecting contact mounted on a plug, adapted whilethe line is in use to be directly'conynected to said contacts andthereby electrically unite them, a test outfit connected on Aone side tosaid common conductor and on the other adapted to be connected to atestcontact for testing and a test-battery for said test-circuit.

14. In a multiple-switchboard exchange,

line-circuits, each connectedto a jack at each board, each jack providedwithv a stripof insulating material having a plug-hole through it,transverse to its front, of the metal part-s of a-spring-jack switchmounted thereon, said parts containing a spring-lever placed transverseto the front of said strip and inthe rear of the plug-hole, and twocontact-pieces, norvmally insulated from each other, said contact-piecesbeing mounted withl their contactsurfaces in the same plane, and on theface in said hole in contact with said spring, a bridging orcross-connecting insulated contact mountedupon a plug and adapted whensaid plug is insertedv into a line-jack to be directly connected to bothof said contacts thereby electrically connecting them, a test receivinginstrument connected for testing, on one side to said common conductorand on the other to a plug or device adapted to be applied tothe othercontact-piece.

MILO G. KELLOGG.

Witnesses:

WALLACE L. DE WOLF, FRA-Nens D. KELLoGG.

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